Does anyone know of a good centralized resource that contains a consolidated list of server specifications relevant to the data center?
Looking for Rack U sizing, power consumption, etc. for different branded servers directly from vendor web sites proves difficult - especially for legacy equipment.
Vendor provided information is usually "absolute maximum", and therefore is largely useless. You need to measure under your conditions and workloads.
It would be very, very hard to tell as so much of power consumption depends on the specifics of your server hardware.
That said, I highly recommend every sysadmin have a wattmeter in their toolkit, like the kill-a-watt.
(source: typepad.com)
Only twenty bucks and it makes this kind of stuff so easy to figure out!
For example, I learned that the web tier servers this very website is running on (Lenovo RS110, specs here), pull:
Idle: doing nothing at windows desktop (unusual, but depends on the server role.. some are light)
96w, 0.85 ampFull New Install Windows Update: 20% on CPU, plus lots of disk activity (I would consider this more or less a typical load)
120w, 1.0 ampFull Load: Prime95 + Update. 100% all 4 CPU cores, plus disk activity (this would be extraordinary load, rare)
175w, 1.55 amp
Of course you need to own the server to turn it on and use this tool on it, but perhaps you can use the tool on similar servers you already own to get an idea of what the power consumption might be of other servers you're planning to buy.
I've seen hardware and Datacenter technicians use Clamp-on Ammeters to measure the actual amperage on a circuit. It will clamp around a wire, so no need to unplug a wire.
Craftsman sells one for $40. I haven't tried this in a Datacenter myself, but I used one to measure the energy used by my fridge, toaster & microwave.
For server rooms and datacenters, I like to use a metered PDU (power strip) which shows current power usage. Yes they are expensive, but it saves staff time and reduces the need to move power cables from circuit to circuit. They are very handy after racking 20 new servers, or when moving the SAN from one circuit to another.
Some of these are network-capable, so you could monitor power usage over the network (Perhaps using Cacti). Again, I haven't done this myself--- but I've seen others do this, and I wish I had the time.
Vendors will list a worst-case nameplate rating, but given the range of configuration options as well as workloads (busy servers draw more power) in just about any server, the actual draw will be widely variable. Best approach is to measure the power use of your gear under a variety of conditions -- the Kill-A-Watt is cheap, and great for 120V gear you can bench-test. You can use a clamp-on meter, but you'll need a breakout cable to do that -- using a standard clamp meter on a normal cable will read pretty close to zero, as the hot and neutral have current flowing in opposite directions, so their magnetic fields cancel out. Megger (and others) make clamp meters designed to work on cables without needing the individual conductors broken out, but it's been my experience that they are far less accurate.
The APC link above is great. If you have mostly Dell, this is a great resource as well.
APC has a UPS selector that might help you. You can select servers. telecom gear, etc.
It doesn't help that there are two different loads you need to be concerned about. The first one, running load, is what most datacenters are engineered around. The second, startup load, is of concern in datacenters where the presence of power is not guaranteed. Generally speaking, most devices have a power-consumption spike as they start up.
As an example of this, I recently installed a new disk-shelf for one of our disk arrays. Running load was in the neighborhood of 300 watts, but startup-load was 540 watts as all those disk drives spun up. Combine that with five other shelves, and you've got a rack that draws 1500 watts during normal usage, and 2700 watts during startup. 1500 can be handled by a normal 15 amp circuit (in 120v areas), but 2700 watts isn't enough even for a 20 amp 120v circuit. If this disk array ever has to power-cycle, I have to make sure that the power is connected to more than once circuit; preferably three to guarantee I won't pop breakers if the power-supplies all chose to draw from the same circuit.
I've used a product suite for years by http://www.21cii.com/. The IT Studio suite includes a libraray of specification for most commercial and enterprise computing hardware and appliances. The tool has way more capabilities than you will likely ever need to use, but the libraries are the real find. You can even override some values and enter your owen, when you need a customized configuration. The tool builds your environment virtually and performs analysis' such as W/SF or BTU total over entire rooms or a sub-zones. The tool even publishes PDU Schedules, checks your breaker to outlet compatibility, and computes total PDU Load, as you build PDUs and RPP panel in the virtual data center. Because it works off an AutoCAD driver, your 'Data Center' can be viewed in real-time scale three dimensionally. It's a little pricey, but a it's a big time saver and ensures fat finger mistakes don't cost you big down the road.